Gap between plunger and barrel

Hi.I am just a guy trying to build an injection machine.It have been running pretty smooth so far,but i ve encountered a problem.I want to order a plunder for a local lathe man,but i cant define a gap between the plunger and the barrel.I have to come up with something in order not to smoothen the barrel inside.That would be far too expensive for me.How do i make a valid order?

hi there,  i made  mine on the  lathe  from  brass.  turned it down  till it fitted snug  and  works well i can send  pic  for you .

Ken ,

Hey @yomvol,


The gap between the barrel and plunger here in the PP workshop is .5mm on either side. So barrel is 26mm and plunger is 25mm.

Hope this helps and gives your lathe guy something to work with 🙂

Could you tell me the exact value?

Brass?Thats a strange choice because it has a strong linear thermo expansion.Why dont you use steel?